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Friday, August 30, 2013

I hope you won't bomb Syria unless you really do have proof that the regime was responsible for the gas attacks. You are dealing with an area outside the day to day experience of most of us in the west.

Many of the Middle East anti-regime organizations deem it completely acceptable to send their young people festooned with explosives to blow themselves up along with their targets.

Many of the anti-regime organizations regularly put their offices and bases in areas crowded with civilians with the sure and cynical knowledge that if they are attacked, there will be lots of civilian casualties that they can use to whip up sympathy for their cause.

Do you really think it is unthinkable that at least one of the organizations that is opposing the Syrian regime could have made the gas attack themselves. These anti-government regimes are highly fractured and often they are more at war with each other than with the regime. One of them could easily have arranged a gas attack at the time that the Syrian government was bombarding an area of a rival faction.

President Obama, your FBI is a very corrupt organization as revealed by Sibel Edmons (Classified Woman) and your CIA and NSA highly incompetent as revealed by WMD's. I imagine that the CIA and NSA is also just as corrupt as the FBI.

You have incredible pressures on you from Kerry and others to attack and I have no idea how you can resist this but I hope you do. This is the test of a truly great man and president.

And just a final thought. If it is proven that one of the factions is responsible for the gas attack, what are you going to do. You certainly can't bomb them. They are too diffuse geographically to be a target for even a targeted bomb.

Don't misunderstand me. I am not defending the Assad regime. It is at least as nasty as the Sadam Hussein regime was in Iraq but you (America) has been made to look foolish in the Iraq affair. One more like that and you will loose all credibility.

Saturday, August 3, 2013

Recently (early 2013) there have been back and forth arguments about
the possibility of a rapid methane emission from the Arctic Continental
Shelves and especially from the very wide shelf off the north coast of Russia. Sea level was 120
meters lower during the last glacial and apparently there is still
permafrost under the sediment of the ocean bottom from this period
despite the overlying layer of water which is above zero degrees
centigrade. This layer is said to be up to 1.5km deep. Although we don't yet have a very good handle on the
subject, it is hypothesized that this permafrost is locking in enough
methane as methane hydrate, either within or below the permafrost, to greatly increase global warming if it was
released suddenly.

Since the permafrost is apparently still there and
has been over the 10,000 years since the last glacial ended, the conduction of heat downward to this
layer must be very gradual and
hence,, so the argument goes,, a sudden belch of methane is unlikely. For the
purpose of this blog, I will assume that such a reservoir does exist and
speculate on a mechanism(s) by which it could be released suddenly.

Before starting, though, we should look at the true strength of Methane
as a green house gas. While it is oft quoted as 20 or 25 times as
effective as Carbon dioxide, this is "on a 100 year basis".
As odd as it seems, instantaneously, methane is more than 100 times as effective as Carbon
dioxide and hence a 4ppm increase in methane in the atmosphere would
have a greater effect in the short term (a few decades) than our present 400ppm Carbon dioxide. Click on the above link to see why this is so. Reverse engineering the figures, I came up with a figure of 140. In other words, the approximately 2ppm methane in the atmosphere at present has the warming effect of 280ppm carbon dioxide. Just recently (Dec 2013) the NSIDC site quoted a figure of x86.

It
should also be noted that ever increasing amounts of methane are being
observed bubbling out of Arctic Ocean. It is possible that this may is due to more intense observation. Whether or not methane emissions are actually increasing will become apparent over the next few years. Curiously enough, despite a likely increase in methane emissions over the past decade or two, methane levels in the atmosphere have hardly increased and this needs some explanation.

This is an exerp. from the NSIDC web site on the subject.

The Siberian continental shelf is a vast region of shallow-water
covered continental crust, comprising about 20% of the global area of
the continental shelf. During the last glacial maximum, much of the
shelf was exposed to the cold atmosphere and froze to a depth of about
1.5 kilometers (about 1 mile). Layers of sediment below the permafrost
slowly emit methane gas, and this gas has been trapped for millennia
beneath the permafrost. As sea levels rose at the end of the ice age,
the shelf was once again covered by relatively warm ocean water, thawing
the permafrost and releasing the trapped methane. Methane is a potent
greenhouse gas but is relatively short-lived in the atmosphere (about 12
years), leading to reduced global warming potential over time. In the
short-term however, methane has a global warming potential 86 times that
of carbon dioxide.

So what mechanisms could lead to rapidly increasing breakdown of Clathrates in or under the permafrost.

The
added 120m layer of water over the Arctic continental shelves will have
added extra stability to any underlying clathrates due to the increased pressure. Therefore a
greater temperature rise will be necessary to
start the disintegration than before the sea covered these deposits . Once enough heat has reached the clathrates
to start this break down, the pressure will begin to rise. If the overlying cap of permafrost is strong enough and continuous enough, this increase in pressure will have a negative feed back on the further break down of the underlying clathrate*.

* Think of
putting a piece of clathrate into a very strong sealed container at room
temperature. As the clathrate begins to break down, pressure in the
vessel increases. The warmer it is, the higher the pressure has to rise before clathrate break down ceases. For instance, clathrates are stable at 17 degrees centigrade at a pressure equal to a depth of 1600m.

The problem arises if pressure
from the methane which has been released from the clathrate is sufficient to crack the overlying permafrost and
create a tunnel or crack up to the ocean bottom. Now instead of the weight of the sediment (SG about 2), the pressure of the overlying water and the mechanical strength of the frozen sediment keeping the pressure on the clathrates, you have only the
pressure of the water column from the ocean surface to the clathrate
layer. Some of the clathrate has already broken down and the methane is just waiting for a breach in the overlying permafrost for it to rise to the surface.

On the other hand clathrates have
latent heat just as does ice which creates a negative feed back on the rate of clathrate break down. Clathrates can only break down as fast as the inflow of
heat allows. Already broken down clathrate will release its methane suddenly but remaining clathrate will break down only as fast as heat can reach it. As more an more gas is evolved,
the tunnelling increases and sea water with it's heat content gains
access to these layers. You have a sort of geyser as in Yellowstone
park. The process accelerates.

You also have an air (methane) lift
effect. Gas rising through any channel between the clathrate deposit
and the bottom of the ocean further reduces the pressure on the
clathrate increasing its break down. The shallower the bottom of the sea where such a break occurs, the greater the reduction of pressure on the clathrate deposit. Now
yet another effect is kicks in.

At some locations along the continental slope, it is likely
that all that is holding the sediment together is the permafrost and
clathrate ice. Once this layer starts to loose it's integrity due to
the break down in the clathrates, small tremors can induce large
slumps, releasing the pressure on large deposits of clathrate. Picture
the land slide on Mt St Helen that released the pressure on underlying
gas-saturated magma. I'm not suggesting anything so dramatic but the
basic principle is the same.

Another factor at play is that the clathrate itself likely caps deeper deposits of free methane. Heat from the centre of the earth seeps upward to meet the "cold" seeping down from the sea floor*. Above about 200C clathrates don't form. On average, temperatures rise 25 degrees per km you go down into the earth. Below the permafrost layer, one would expect to find free methane. If methane is seeping up from deep deposits of liquid or gas hydrocarbons, from coal measures or from shale, as it hits the deep cold pore water of sediments it is absorbed by water and forms clathrates. This caps underlying methane and any crack is quickly sealed as methane seeps up such cracks and forms clathrate. It has been observed that some of the methane seeping out of permafrost areas on land is young methane (likely from the break down of organic material) and some is old (likely from deeper hydrocarbon deposits). Such rising methane will sit below its cap of clathrate ice just waiting to be released.

When it was initially
calculated how fast our ice sheets could melt, only thermodynamics was
taken into account. At that time it wasn't realized the effect of, for instance, moulons increasing
the slide of ice into the sea and it also wasn't realized that a warmer
ocean was melting floating ice sheets from below. As these ice sheets disintegrated, ice flow to the ocean increased and the contribution to sea level of ice was larger than thermodynamic considerations would have predicted.

We may
be making the same mistake here with clathrates as we only consider how fast heat can
be conducted down through the layers of sediment toward the deposits of
clathrates. We could be in for some wee surprises as some of the above
"convection" type phenomenon cut in.

ps. There is another wrinkle in this story. If the permafrost isn't conventional permafrost; in other words frozen ground, but is itself methane clathrate; ie permafrost with a methane component dissolved in it, it will not melt at just above 00C. It's melting temperature will depend on how much methane is in the ice and on what depth, and hence what pressure, it is at. It would be very instructive to have a few hundred cores taken on the Arctic continental shelf to see what is actually down there and at what depth. Methane clathrate can exist at 200C with sufficient pressure. Such cores would allow a much better estimate of how prone we are to a sudden release of methane.